Method for making bristles for a hairbrush

ABSTRACT

The invention relates to a hairbrush, bristles for use in a hairbrush and a method of producing a hairbrush and such bristles. The invention discloses in particular a method of producing a bristle, in which mouldable material is introduced into a multi-part mould which can be separated into its individual parts, and a bristle having a bristle head, a bristle shank and a bristle foot is produced and a bristle shank is moulded using a first mould part, wherein mouldable material is introduced into a first cavity of the first mould part and subsequently removed from the first cavity of the first mould part, wherein the first cavity of the first mould part is maintained and the bristle foot is moulded using a second mould part and a third mould part, wherein the second and third mould parts together form a second cavity, of which the shape corresponds essentially to the shape of the bristle foot which is to be moulded, and the second cavity is filled with the mouldable material and the second and the third mould parts are subsequently separated, and the bristle head is moulded using a fourth mould part and fifth mould part, wherein the fourth and fifth mould parts together form a third cavity, of which the shape corresponds essentially to the shape of the bristle head which is to be moulded, and the third cavity is filled with the mouldable material and the fourth and the fifth mould parts are subsequently separated.

The invention relates to a hairbrush, bristles for use in a hairbrush,and method for the production of a hairbrush and such bristles. Theinvention can be used in a multiplicity of completely differenthairbrushes. It is even possible for the bristles described herein to beused in brushes that are not used or are not predominantly used for thebrushing of hair. In particular it is also suitable for the bristles tobe used in a massage brush. Their use is likewise possible in a haircare device that additionally heats the hair, for instance by means ofhot air or a hot contact surface. Corresponding devices are marketed asso-called stylers or curlers.

GB 601,371 (Denman) discloses a hairbrush with non-metallic bristles.The bristles taper towards the tip and have a bristle foot that allowstheir firm anchoring in a rubber mat, in that the bristles with the tipare first pushed through openings in the mat, and pressure is exerted onthe bristle feet from the brush side by means of an corresponding brushbody.

A method for the production of bristles is known from DE 2155888. Amulti-part separable mold part is disclosed there with which a bristlewith a bristle foot and a bristle shaft can be molded. The methodenables bristle shafts to be produced that are at least in principleflash-free, but require a laborious stretching and a complex mold part.In spite of the complexity of this mold part, however, freely selectableshapes for the bristle foot or bristle head cannot be produced.

The object of the present invention is to offer bristles and brushes aswell as methods for their production that are improved with respect toprior art. The bristles and brushes should have a particularly gentleeffect on hair and scalp. The production methods are to be suitable formass production; they should be cost-effective and produce little waste.In particular the methods should provide bristles and brushes that aresafe and gentle for use, even if production standards are not perfect.

These objects are achieved by a method for the production of a bristleaccording to claim 1, by a method for the production of a brushaccording to claim 9, and by a bristle according to claim 10 or 11, aswell as a hairbrush according to claim 14. Preferred embodiments, bymeans of which the objects are achieved particularly well, are describedin the Subclaims.

The use of a multi-part mold part that can be separated allows optimizedmold cavities to be made available for different bristle parts. Thebristle shaft blank is molded in the mold cavity of a separate moldpart. To this end moldable material is introduced into the mold, whichfor this purpose as a rule has an air outlet channel opposite to thefeed opening for the moldable material. The mold cavity will usuallytaper away from the feed opening, i.e. the mold cavity has a smallercross-section at a point further away from the feed opening. Accordinglythe bristle shaft blank is generally molded in such a way that it tapersin the direction of the bristle head.

The invention is suitable for the molding of bristles made of allcurrent moldable materials, i.e. all suitable plastics, and inparticular polyamides. A preferred material is aliphatic polyamides, inparticular those that are commercially available as “nylon”. Suchaliphatic polyamides are relatively insensitive to heat, which allowsthe bristles to be used in a hairbrush while the hair is heated, forinstance by a hair dryer.

However, it is known in particular for the preferred aliphaticpolyamides that they tend to form a flash readily, since they flowparticularly well in multi-part mold parts. Therefore if the mold cavityfor the bristle shaft were to be formed in a two- or multi-part moldpart, a flash would remain behind when demolded. However, such a flashon the bristle shaft damages the hair and in addition soil collectsthere readily. This leads to a hairbrush that is not very hygienic andnot very gentle.

The after-treatment of a bristle shaft would be conceivable, for exampleby deflashing. One possibility for deflashing is the treatment of moldedbristle shafts with abrasive agents. However, this step istime-consuming and expensive and can also lead to an increased roughnessat other points of the bristle shaft. Alternatively or in addition, thebristle shaft could be frozen for the purpose of deflashing. The verytough aliphatic polyamide material can be deflashed more easily byfreezing. However, this step is obviously likewise expensive.

According to the method presented, the bristle foot is molded with twomold parts, which together form a mold cavity. This mold cavity, whichis formed from two mold parts, corresponds essentially to the shape ofthe bristle foot to be molded. It is filled with the moldable materialand the two mold parts are subsequently separated.

Generally, the bristle foot is formed of the same moldable material asthe bristle shaft. The mold cavities for bristle shaft and bristle footthereby form a connected mold cavity, which is filled with a moldablematerial in one step. However, the molding of bristle shaft and bristlefoot from a different material is also conceivable.

According to the method presented, the bristle head is likewise moldedwith two mold parts that together form a mold cavity. This mold cavity,which is formed from two mold parts, corresponds essentially to theshape of the bristle head to be molded. It is filled with the moldablematerial and the two mold parts are subsequently separated.

Generally, the bristle head is formed from the same moldable material asthe bristle shaft and/or bristle foot. The mold cavities for bristleshaft and bristle head thereby form a connected mold cavity, which isfilled with a moldable material in one step. However, the molding ofbristle shaft and bristle foot from a different material is alsoconceivable.

For the removal of the bristle shaft from its mold part, it can be movedaway along the axis of the formed bristle relative to the mold partsthat hold the bristle foot. Then the two mold parts that hold thebristle foot are separated. This movement of the mold parts enables asimple removal of the bristles without additional devices.

However, with a bristle shaft that tapers in an axial direction, theremoval direction is determined by this tapering. Generally, the bristleshaft will taper in the direction of the bristle head. The removal fromthe mold then should take place in the direction of the bristle foot. Ina method by way of example, therefore, the two mold parts that havemolded the bristle head are first released. Then the two mold parts thathave molded the bristle foot are moved relative to the mold part for thebristle shaft. Then the two mold parts that have held the bristle footare moved apart from one another so that the bristle is situatedcompletely outside the mold. Particularly with this removal method, itis advantageous if the bristle head is not too thick. In particular, amethod is possible in which the largest diameter of the bristle headmeasured radially to the longitudinal axis of the bristle is smallerthan the smallest diameter of the bristle shaft measured radially to thelongitudinal axis of the bristle. In particular the largest diameter ofthe bristle head measured radially to the longitudinal axis of thebristle can be smaller than the smallest diameter of the bristle shaftmeasured radially to the longitudinal axis of the bristle by a factor ofat least 0.5 or 0.75 or 0.8 or 0.9. With such a method the bristlematerial can be largely or completely inelastic, since the geometry ofthe bristle in no way prevents the removal. However, if a sufficientlyelastic material is used, the diameter of the bristle head can also begreater than the diameter of the bristle shaft (respectively measured asabove).

Due to its advantages in the production method, as well as to itsadvantages in use, a bristle is also advantageous in which the largestdiameter of the bristle head measured radially to the longitudinal axisof the bristle is smaller than the smallest diameter of the bristleshaft measured radially to the longitudinal axis of the bristle.

It must be taken into account that brushes are a reasonably pricedregularly replaced article of daily use. Thus a brush should not be tooexpensive. Therefore with the enormous number of bristles to beproduced, it is particularly important that a reasonably priced massproduction method be taken into account. Mold part that can beseparated, which together form a mold cavity, regularly leave behind asmall flash along the parting line. In high-quality and new mold parts,this flash is small. However, particularly in a reasonably priced massproduction it is also necessary to use reasonably priced mold parts overa certain service life. This leads to distinct flashes, which have thedisadvantages described above when used as a hairbrush.

On the other hand, the molding of the bristle shaft together with thebristle foot in a single mold part is not without other difficulties.The bristle shaft must then taper over its entire length and the bristlefoot must also do this, so that a complex bristle shape cannot beproduced. A simple bristle shape of this type, as is also known from GB601,371 (Denman), however, leads to certain additional requirements forthe brush. Denman discloses a relatively complex brush body, in whichthe bristles are supported over their entire surface. Although thebristles can bend sideways, they cannot bend back onto the brush alongtheir longitudinal axis. Such a bending back of the bristles, i.e. aresilient mounting, however, is considerably gentler for instance forthe scalp, when the brush is used as a hairbrush.

The present method allows bristles to be produced for a resilientmounting of this type. The resilient mounting of the bristles can beachieved if the bristle foot has an undercut with which the bristle footcan be fixed both on the upper side and also on the underside of asupport material.

Such a support material can for instance be an elastic rubber mat, whichis set in the bristle body in an elastically pretensioned manner. Thisrubber mat then imparts a resilient elasticity to each individuallyinset bristle. The bristles can bend back along their longitudinal axis(and again be pressed in the direction of the hair by resilientelasticity) and also can yield in each axial direction thereto. Theability to design a complex molded bristle foot therefore allows gentlerbrushes to be produced.

The bristle shape, which is complex compared to the Denman bristles,allows a simpler brush shape, but one that nevertheless enables a gentlecombing. Moreover the bristles have only a few flash-containing areas.The bristle shaft, which is flash-free over its entire length, is gentleto the hair.

The method for producing a bristle can also include further steps. Inparticular it is possible to work the profile of the bristle shaft blankfurther. Such a working can comprise coloring, sanding, smoothing, orpolishing of the bristle shaft blank. In particular the working of thebristle shaft blank in the area of its head is also possible.

It is also possible in a further production step to provide the bristleswith a covering material at the bristle head. In particular it ispossible to provide the bristle heads with varnish, for instance in theform of small drops of varnish that produces a thickening and roundingof the bristle head.

Such varnished bristle ends are known. However, with lengthy use ofbristles and brush, they regularly lead to the problem that the coveringmaterial falls off the bristle. This problem can be combated byproviding a bristle head with a suitable profile. In the describedmethod, the third mold cavity can be designed independently of the othermold cavities, in order to select the profile in a suitable mannerBristles whose bristle head has an undercut or a constriction arewell-suited.

The method can therefore be used advantageously to produce at least onebristle that includes a bristle foot, a bristle shaft, and a bristlehead of respectively different profile, and in which the bristle foothas an undercut, the bristle shaft is flash-free, and the bristle headhas a bristle head covering.

In particular a bristle is also suitable that includes a bristle foot, abristle shaft, and a bristle head of respectively different profile, andin which the bristle foot has an undercut, the bristle shaft isflash-free, and the bristle head has a bristle head covering, and thelargest diameter of the bristle head measured radially to thelongitudinal axis of the bristle is smaller than the smallest diameterof the bristle shaft measured radially to the longitudinal axis of thebristle. In particular the largest diameter of the bristle head measuredradially to the longitudinal axis of the bristle can be smaller by afactor of at least 0.5 or 0.75 or 0.8 or 0.9 than the smallest diameterof the bristle shaft measured radially to the longitudinal axis of thebristle. In such a bristle, the bristle head can also have a neck or anundercut.

The present method allows bristle heads of any shape to be configured ina separate mold part. In the molding by means of the two shared moldparts, however, in any case under certain circumstances of massproduction, a flash can arise. It is possible to design the bristle headcovering such that the bristle is particularly gentle even whenweakening in the production method. In this context it is possible todesign the bristle head covering such that it completely surrounds thebristle head, in so far as it was in the third mold cavity. Typicallythe bristle head covering thereby surrounds not only the end of thebristle head, frequently in the form of a sphere, but also the upperpart of the shaft. It is possible for the bristle head covering toextend axially for a certain length. In particular a bristle can beadvantageous in which the bristle head extends axially over a firstlength (l_(k)) and the bristle head covering extends axially over asecond length (l_(h)) and the second length (l_(h)) is greater than thefirst length (l_(k)) by a factor of at least 1.2 or 1.5 or 2 or 2.5.

The method can be used to provide bristles with a bristle head coveringin which the largest diameter of the bristle head covering (20) measuredradially to the longitudinal axis of the bristle is greater than thesmallest diameter of the bristle shaft (14) measured radially to thelongitudinal axis of the bristle. In particular the largest diameter ofthe bristle head covering measured radially to the longitudinal axis ofthe bristle can be greater than the smallest diameter of the bristleshaft measured radially to the longitudinal axis of the bristle by afactor of at least 1.1 or 1.25 or 1.5 or 2.0 or 2.5.

The method for the production of bristles can be part of a productionmethod for brushes. A method for the production of a brush is possiblein which bristles are produced in a method according to one of thepreceding claims, and these bristles with their bristle foot are insetinto a bristle support cushion and the bristle support cushion is usedin a brush.

A hairbrush that was produced according to one of the methods describedhere can also include additional hair treatment devices. In particularit is possible for the hairbrush to additionally include an ionapplicator. Such an ion applicator can counteract the static charge ofthe hair. Hair is typically positively charged, so that the applicationof negative ions on the hair is useful. Such an ion applicator can beline-powered or battery-powered. For a particularly gentle and handyhairbrush, a battery-operated applicator for negative ions is suitable.

This and further features of the invention are shown not only by theclaims but also by the following description and/or the associateddrawings, wherein the features can form the subject matter of theinvention in various combinations and sub-combinations together as wellas individually, notwithstanding their inclusion in the claims. Theinvention is described in more detail below based on preferred exemplaryembodiments and associated drawings. The drawings show:

FIG. 1 A longitudinal section through the mold parts along thelongitudinal central axis of a bristle.

FIG. 2 A longitudinal section through a bristle according to theinvention.

FIG. 3 A longitudinal section through a bristle according to theinvention that has a bristle head covering.

FIG. 4 A cross-section through a brush.

FIG. 1 shows a longitudinal section of a bristle (10) in a mold part.The longitudinal section is selected along the longitudinal axis (L) ofthe bristle. The bristle head (12), the bristle shaft (14) and thebristle foot (16) are visible. The bristle shaft (14) is formed in afirst mold part (30). The bristle foot (16) is formed between a secondmold part (32) and a third mold part (34), which jointly provide asecond mold cavity (42). The mold cavity (42) is designed so that thebristle foot (16) has an undercut (18). The bristle head is formedbetween the fourth mold part (36) and the fifth mold part (38), whichjointly provide the third mold cavity (44). The removal of the bristlefrom the mold parts can take place in that first the fourth mold part(36) and the fifth mold part (38) are moved apart from one another inthe axial direction (A) and thereafter the second mold part (32) and thethird mold part (34) are moved away from the first mold part (30) in thelongitudinal direction of the bristle (L). Then the second mold part(32) and the third mold part (34) are also moved apart along the axis(A).

FIG. 2 shows a bristle (10) that can be produced according to the methoddisclosed here. The bristle (10) has a flash-free bristle shaft (14)that is limited upwards by a bristle head (12) and downwards by thebristle foot (16). The bristle shaft (14) tapers towards the bristlehead (12) between the bristle foot (16) and the bristle head (12). Thebristle foot (16) has an undercut (18). With this undercut (18), thebristle (10) can be anchored in a bristle support. The bristle head isthereby designed essentially axial-symmetrically to the longitudinalaxis (L) of the bristle.

FIG. 3 shows another bristle (10) with a bristle head covering. Itsshape corresponds essentially to the bristle of FIG. 2. However, abristle head covering (20) is additionally applied to the bristle head(12). This leads to a thickening of the head compared to the bristleshaft (14), which promotes a gentle hair and skin treatment. The bristlehead diameter (d_(k)), which actually is to be determined in the radialdirection to the longitudinal axis, with a spherical head profile asshown can also be measured in a different direction. With this roundhead shape, the first length (l_(k)) can conveniently be determinedbetween the upper end of the bristle head and the level of the narrowestconstriction between bristle head and bristle shaft.

FIG. 4 shows a cross-section through a brush that goes through thebristle field of the brush (40). In this cross-section the bristlesupport (42) and the brush body (44) are seen in which the bristlesupport (42) is inset. The bristle support (42) can be inset in aresiliently pretensioned manner, so that the bristles (10) contained inthe bristle support (42) are mounted in a resiliently elastic mannerwith respect to the bristle body (44). The bristles (10) can move alongtheir respective longitudinal axes towards the brush body (44) and canmove back again resiliently in the direction of the hair, for instance.They can also move in an axial direction.

The brush (40) shown is additionally provided with an ion applicator(50). The ion applicator is attached at the back of the brush body,therefore is turned away from the bristle support (42) at the side.

What is claimed is:
 1. A method for the production of a bristle (10) foruse in a hairbrush (40), in which moldable material is introduced into amulti-part mold that can be separated, and a bristle (10) with a bristlehead (12), a bristle shaft (14), and a bristle foot (16) is produced,said method comprising a bristle shaft (14) is molded with a first moldpart (30), wherein moldable material is introduced into a first moldcavity (40) of the first mold part (30) and is subsequently removed fromthe first mold cavity (40) of the first mold part (30), wherein thefirst mold cavity (40) of the first mold part (30) is maintained and thebristle foot (16) is molded in a second mold part (32) and a third moldpart (34), wherein the second and third mold parts together form asecond mold cavity (42) whose shape essentially corresponds to the shapeof the bristle foot (16) to be molded, and the second mold cavity (42)is filled with the moldable material, and the second and the third moldparts are subsequently separated, and the bristle head (12) is molded ina fourth mold part (36) and a fifth mold part (38), wherein the fourthand fifth mold parts together form a third mold cavity (44) whose shapeessentially corresponds to the shape of the bristle head (12) to bemolded, and the third mold cavity (44) is filled with the moldablematerial, and the fourth and the fifth mold parts are subsequentlyseparated prior to removing the bristle from the mold.
 2. The methodaccording to claim 1, in which the largest diameter of the bristle head(12) measured radially to the longitudinal axis of the bristle issmaller than the smallest diameter of the bristle shaft (14) measuredradially to the longitudinal axis of the bristle.
 3. A method accordingto claim 1 in which the bristle (10) is further worked.
 4. A methodaccording to claim 3, in which the bristle (10) is further worked in thearea of the bristle head (12).
 5. A method according to claim 4, inwhich the profile of the bristle shaft blank is provided with a bristlehead covering (20) in the area of the head.
 6. A method according toclaim 5, in which the bristle head covering (20) completely coveringsthe bristle head (12), in so far as it was in the third mold cavity(44).
 7. A method according to claim 5 in which the largest diameter ofthe bristle head covering (20) measured radially to the longitudinalaxis of the bristle is larger than the smallest diameter of the bristleshaft (14) measured radially to the longitudinal axis of the bristle. 8.A method according to claim 7 in which an undercut (18) is provided atthe bristle foot (16).